Couldn't load chunk java.lang.NullPointerException When Loading Region File

Seemingly valid regions are not being loaded into the game. NBT Editor can read the chunks properly but Minecraft cannot and throws this error into the console:

Couldn't load chunk [9, 4]
java.lang.NullPointerException
    at caj.a(SourceFile:122)
    at caj$$Lambda$2993/695222020.accept(Unknown Source)
    at cap.a(SourceFile:249)
    at cap$$Lambda$2995/2002450762.accept(Unknown Source)
    at it.unimi.dsi.fastutil.ints.Int2IntOpenHashMap$MapEntrySet.forEach(Int2IntOpenHashMap.java:927)
    at cap.a(SourceFile:249)
    at caj.h(SourceFile:121)
    at cau.a(SourceFile:101)
    at wp.j(SourceFile:512)
    at wp$$Lambda$2950/1413693670.get(Unknown Source)
    at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1582)
    at aip.h(SourceFile:144)
    at aip.v(SourceFile:118)
    at xb$a.v(SourceFile:550)
    at xb.d(SourceFile:274)
    at net.minecraft.server.MinecraftServer.aZ(SourceFile:730)
    at net.minecraft.server.MinecraftServer.v(SourceFile:718)
    at aip.c(SourceFile:127)
    at net.minecraft.server.MinecraftServer.u(SourceFile:703)
    at net.minecraft.server.MinecraftServer.a(SourceFile:490)
    at edj.a(SourceFile:88)
    at edj.d(SourceFile:104)
    at net.minecraft.server.MinecraftServer.run(SourceFile:627)
    at java.lang.Thread.run(Thread.java:745)